ABSTRACT This report containa a description of the mission, organization and activities of Task Unit 6, Task Group 7.1, Joint Task Force SEVEN, during Operation Hard- tack, Task Unit 6 was charged with the responsibility of providing radiological safety support for the Scientific Task Grour, TG 7.1. The various chapters are devoted to a discussion of the activities ongaged in by the Task . Unit and the organization necessary to provide adequate radiological safety support for a weapons test operation of the magnitude of Operation Hardtack. Radiological survey results of the atolls following firing of the various devices are presented. Special problems arising during the operation are discussed.